For the past eight years, Glassdoor has given workers a place to discreetly share information about their salaries and their work environment. The site now attracts 33 million people each month and has amassed reviews, ratings and salary information for around 600,000 companies in 190 countries. Glassdoor is now harnessing all of that data it’s collected — from its salary database in particular — to give users a better understanding of whether or not they’re being paid fairly. The free “know your worth” tool that’s being rolled out in beta this week asks users to input some basic information including their job title, employer, current salary, location and relevant work experience. With that, Glassdoor is using a proprietary machine learning algorithm to calculate an individual’s “market value” — the median…